Understanding the Declination Scale on HEQ5 mount.

[philsail1]

Dear All,

I had the SW200 out on Tues (22nd) - but a bit too late to catch the Moon and Saturn in Field of view of even my 40mm Plossl. However, I did play about with aligning the Pole star, and actually used the setting circles for the first time in my life (I used to have the SW130mm Newt, but never got to using them on that). Success! I managed to latch on to a couple of stars - the names of which I can't remember! (I know one was the double, double in Ursa Major), oh! and the other was lower down from that constellation. I did not get them quite spot on, but near enough to pick up in a 25mm eyepiece. I tried to find the M31 Galaxy near Ursa Major, but could not. However, I would like to thank all of you who kindly gave advice on my "understanding and using setting circles" question a few days ago. Your replies were very encouraging - and confidence inspiring. What I would like to ask now is:- do you have any advice on understanding the actual degrees scale on the "Declination" setting circle. This scale appears to be numbered in degrees from "0" to "90" then it starts again, so there appear to be 4 sets of "0" to "90" degree portions. I,m not quite sure how to use this scale. Also the smaller "Polar Scope" setting scale (which wraps around the Polar Scope), and the thin setting ring. I have read one needs to set these to cope with the East or West offset of where one lives. I'm not sure about how to set these. Am I asking for answers to too many aspects at once? Please advise if I am and I will separate the questions to new topics. I have been studying the likes of "Lone Wolfs" Polar Setting" instructions, and the chap (Steve) from "Chantonbury Observatory's" advice, but I still cannot quite grasp the above aspects. I know I need to master these settings to be able to find the more fainter objects in the night sky.

I eagerly look forward to hearing from anyone.

Regards,

Philsail1

[Astroman]

The Declination is much the same as Latitude on Earth. It goes from zero at the equator up to 90º at the north pole and down to -90º at the south pole. This is what the numbers represent. If your scope is pointing south and above the equator, you'll use one set of positive declination numbers. Pointing north and above the equator should use the other set of positive numbers and vice versa.

HTH.

[daz]

Phil

The scale around the polar scope is not desperately accurate and needs an awful lot of fiddling.

I (and others) find it easier to :

rotate the mount in RA until the image of Ursa Major matches what you see in the sky

then adjust the mount in ALT and AZ until the pole star is in the little circle

This will give you a polar alignment good enough for visual work

[themos]

Major -> Minor?

[Macavity]

The combination of "limbo dance" technique and trying to illuminate the graticule, (albeit on an EQ3-2) always defeated me. But I found that the "random" error of such mounts (beyond these "setup" problems) was actually quite SMALL. They usually "come back to about the same place" following random rotations.

Once you have a "good" setup, I found it was worth while "recording" it. Check (adjust) the declination scale to match the sky. You can then look declination values up, for bright objects, in a Star Atlas, and "Scan in RA" to (often!) find them visible in a half-decent finder.

To speed up setup procedure, I bought a few basic tools - Magnetic Compass, "DIY" (or digital) levels. If you have a semi-permanent setup (patio!), draw LINES/CIRCLES on the ground to help with intial positioning of the tripod etc. Neighbours probably think you're a "Satanist" - (Or just plain "nuts"?) anyway.

[philsail1]

Thanks once again to:- "Astroman" for clarifying the 90 degree quadrants on the Declination scale - use one set if my scope is pointing South and the other if it is pointing North.

"Daz" (and others) for the advice not to worry to much about the scale around the Polar Scope, and simply line up the reticule similar to how the real constellations lie in the heavens. (This is the advice that "Captain Chaos" gave me a few days ago.

Last but not least to "Maccavity" I went a bit further than just mark the patio - after lining up the Pole Star, I drilled three small shallow holes. Fully braced out, the ends of the tripod legs just sit nicely.

Thanks again for all your advice here - it doesn't half cut down on a lot of frustration! (and one doesn't feel alone under the stars!)

Regards,

Philsail1

P.S. I don't know if you know, but I found quite an interesting site on the internet - almost totally devoted to HEQ5 maintenance and modifications. I think the guys Canadian. The site is "ozastro.dyndns.org"

[Kaptain Klevtsov]

He THE MAN Philsail.

Captain Chaos

[hix]

Hi Guys,

I just wanted to piggy-back onto this thread, as my questions are pretty much of the same vein.

I managed to get to Grips with aligning the axis to NCP [on an HEQ5] after much head-scratching. I too founf the lonestar page and the polar-finder exe very useful in understanding the concept.

I am now trying to comprehend how the scales would enable me to navigate the sky?

When i have the polarscope aligned with NCP how do i go about getting the plate that the dovwtail mounts onto aligned so the scales mean anything?

The manual told me that when i had polar aligned the mount then it would be lined up with polaris. Unfortunately it is the RA axis[? that the right one] that is aligned but the mount plate is at 90 deg to the scope [ a necessity as the acope peers through a hole in the mount.

How now do i set the scales so that if i looked up a star i could adjust the mount to roughly the right position?... Sorry if my explanation isn't very clear but i can't edit diagrams at work otherwise you'd have had the whole lot backed up by pics....

[daz]

Adrian

Next step then is to calibrate the setting circles. You now need to rotate both axis and point to a bright star, something like Artcurus or Vega.

Look up the coordinates of the star on the web / planetarium software

Now unlock the setting circles and rotate them only so that the marker points to the coordinates given in the previous step

And that's it.

You can now move to another object by looking at the coordinated on the starmap and rotate the scope in both axis until the markers point to the new coordinates, then your new object should be in the field of view.

Again, as before, the circles are not the most accurate things in the world, but, you should be able to see the object in a low power EP.

HTH

[hix]

Pretty logical then really. Can you get charts that will give the approx settings for a certain star at aa date/time? I have a free stellaruim program that i downloaded [can't rememer the name of it - it uses openGL and there's a wiki on it] which gives co-ordinates. Problem is i have to travel to look at stuff and don't have any space in the car as it is so i can't start dragging everything out to the dark site....

Or is it just a case of pre-planning what to look at and getting co-ordinates for a time preiod?

Is there a site that i can get them from? [whiilst at work ]

Sorry about typos but don;t have time to correct as busy working-ish

[themos]

Can you get charts that will give the approx settings for a certain star at aa date/time?

The RA/DEC settings are date/time independent for a certain object. They vary from epoch to epoch because "proper motion" shifts the nearby stars compared to the distant "fixed" ones.

The star Sadr, Gamma Cygni, for instance, is at

RA 20h 22m 31s

Dec 40° 16' 47"

for Epoch 2007.5

Its azimuth and altitude will vary through the night but the RA and Dec won't.

[proflight2000]

I just asked the wife if i could drill 3 little holes in my patio as I think thats a great idea, she huffed and pufffed and then said "NO" i ask ya, 3 little holes.